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G. BRAMBAGH.

Patented Nov. 5, 1889.

A TTORNEY KEY BOTTOM FOR PIANOS.

(No Model.)

.4 z 2 4 w i a w WITNESSES:

UNITED STATES PATENT OFFICE.

CARL BRAMBACH, OF NElV YORK, N. Y.

KEY-BOTTOM FOR PIANOS.

SPECIFICATION forming part of Letters Patent No. 414,488, dated November5, 1889.

Application filed May 11, 1889.

Serial No. 310,409. (No model.)

.To all whom it may concern.-

Be it known that I, CARL BRAMBACH, of thecity, county, and State of NewYork, a citizen of the United States, have invented certain new anduseful Improvements in Key-Bottoms for Pianos, of which the follow ingis a specification.

This invention relates to an improved keybottom regulator by which thekey-bottom can be readily set when the same is getting out of regulationby a change of atmosphere or any other cause, the regulating being accomplished with great facility and at a considerable saving of time andlabor. My improved regulator is designed for the purpose of overcomingthe warping of the key-bottom and for readjusting the keys either to--ward or away from the action, as may be required.

The invention consists of a key-bottom regulator consisting of akey-bottom having transverse slits at the center and at intermediatepoints, and of two longitudinal bracket-bars that are attached to thebottom of the keeper and connected at their inner surrounding parts by aright-and-lefthand screw, so as to be adjusted relativelyto each otheras required by theproper adj ustment of the keys.

In the accompanying drawings, Figure 1 represents a front elevation of akey-bottom with my improved regulating device. Fig. 1 is an enlargeddetail View of the adjusting-screw. Fig. 2 is a vertical transversesection of the same on the line :20 :13, Fig. 1; and Fig. 3 is amodified construction of an adjusting-screw for the bracket-bars of thekey-bottom.

Similar letters of reference indicate corresponding parts.

In the drawings, A represents the key-bottom, which is provided at thecenter and at one or more intermediate points between the center andends with transverse slits or notches a, which extend from the upperedge in downward direction, the center of the slit abeing of greaterdepth than the intermediate slits, as-shown in Fig. 1. The key-bot tomis supported on two independent longitudinal bracket-bars B, which arescrewed to the, under side of the key-bottom and located below therecess at the rear ends of the key levers. The inner ends of thebracket-bars B B are each provided with a downwardly-extending flangel), which are con nected by a right-and-left-hand screw 0, having asquare head for the tuning hammer.

. In place of the right-and-left-hand screw, any

other adj Listing-screw may be used, as shown in Fig. 3, in which caseone end of the screw must be mounted in the flange b of one of thebracket-bars, while the threaded shank of the screw engages the flangeof the other bracket-bar.

\Vhen the key-bottom has warped upward or downward for some reason orother, so that the key-levers change their relative positions to theaction, the proper position of the key-bottom is restored by turning theright-and-left-hand connecting-screw G with the tuning hammer, wherebythe key-bottom is lifted and the keys adjusted. The eifect of theadjustment of the screw 0 is greatest at the center and smallest at theends of the key-bottom, which corresponds to the usual warping of thekey bottom.

The slits in the key-bottom may be dispcnscd with; but in this case theregulatingbars have to be of greater thickness, so as to produce theadjustment of the key-bottom; but I prefer the use of slits, as theregulating of the key-bottom is thereby facilitated. The key-boardregulator has therefore twofold purposes-first, supporting thekey-bottom and keys in proper position, and, secondly, for adjusting thewarp in the bottom, which is accomplished by considerable saving in timeand labor by a simple application of the tuning-hammer without requiringa of the key-bottom, substantially as set forth. 10o

- 2. lhe combination, withakey-bottom hav- In testimony that I claim theforegoing as ing one or more transverse slits or notches, my inventionIhave signed my name in presof longitudinal bracket-bars attached to theence of two subscribing witnesses.

under side of the key-bottom, and a right-and- CARL BRAMBACH. 5left-hand screw connecting the inner ends of Witnesses:v

the bracket-bars for regulating the key-bot- MARTIN PETRY,

tom, substantially as set forth. A. R. ANGUS.

